The present invention relates to elevator installations with a plurality of individually movable elevator cars and a method of operating such elevator cars.
Every elevator installation occupies a certain proportion of the space in a building which depends on the amount of traffic. The greater the amount of traffic, and the higher the building, the more space the elevator installation needs in relation to the usable surface area (net usable surface area) of the building. The performance of an elevator installation can be expressed as its so-called handling capacity. The handling capacity indicates how many persons can be transported per minute in an office building when the amount of traffic is high, for example at the start of a working day.
It is of great interest to minimize the space required by an elevator installation.
There are various methods of readying and operating more than only one elevator car in one elevator hoistway, of arranging several parallel elevator hoistways of an elevator installation, and of elevator cars transferring from one elevator hoistway into another elevator hoistway.
It is a disadvantage of the known elevators with several elevator hoistways that changing hoistways mechanically is very complex and in many cases proceeds only slowly. Consequently, when the amount of traffic is high, the handling capacity is limited.
From the European published patent application EP 1360718-A2 an elevator installation has become known having several elevator cars which have an autonomous linear drive on the car that makes it possible for the elevator cars to move independently in a vertical direction in the elevator hoistways. The elevator cars are so made that a horizontal movement can also be reliably executed.
Conventional elevator installations are known which, for the purpose of increasing the handling capacity, are equipped with a so-called double-deck car. A double-deck car is an elevator car with two passenger compartments arranged one above the other. Such a double-deck car can, when it stops at a boarding zone of the elevator installation, be loaded/unloaded simultaneously from two floors. By this means, the handling capacity is sharply improved. However, it has become apparent that a method with double-deck cars also brings disadvantages. Such disadvantages are that such an elevator installation cannot be deployed flexibly because the entire double-deck car must always be moved even if only a small transportation capacity is necessary, and that both car decks must interrupt their travel if a halt needs to be made at a floor for passengers of one car deck. Furthermore, the distance between the decks of the double-deck car must take account of the distance between the floors. In many cases, the distance between the individual floors is not equal, which requires complex measures on the double-deck car.
It is a disadvantage of the known elevator installations with several elevator cars traveling in one hoistway that the transportation capacity is limited by a relatively small number of elevator cars departing from a main stop per unit of time. The maximum achievable number of cars departing per unit of time is limited inter alia by the time needed for opening and closing the doors and for allowing the passengers to exit and board the elevator car.